Ballistic helmets are well known in the prior art for use by persons to protect them against serious injury from shrapnel and other missiles. Most modern ballistic helmets are made from a plurality of plies of ballistic material which are laid up in a mold and shaped to the configuration of the helmet.
A material which is eminently suited for use in making ballistic helmets is one which is made from one of the "aramids" which include aromatic polymide resins developed by E.I. duPont de Nemours and Company and sold under the trademarks "Kevlar" and Nomex". This material is relatively expensive. In addition, a considerable quantity of material is used in making up a helmet shell owing to the fact that a relatively large number of plies are required to produce a helmet affording the desired degree of protection. It will be apparent that the most efficient use of the available materials in making up the individual plies is highly desirable.
Generally speaking, two methods are known in the prior art for forming blanks from which the individual plies of the helmet body can be made. In the first of these methods which is exemplified by the disclosure of Daly U.S. Pat. No. 2,532,442, individual unitary blanks are custom cut from the ballistic material prior to being laid up in the forming mold. While this method results in a high quality method having good ballistic properties, it does not make efficient use of the basic material, much of which is wasted in the custom cutting process. In the second method which is exemplified by Grick U.S. Pat. No. 4,596,056, a plurality of individual pieces are joined together by any suitable means to form the blank which is laid up into the mold. While this method permits a more efficient use of the available base material it is relatively complicated and time consuming. In addition, under certain circumstances the pieced up plies have not met customer specifications.